1. Field of the Invention
The present invention relates to fuel injection valves connected to an automotive internal combustion engine for injecting fuel into combustion chambers of the engine. More specifically, the present invention is concerned with the fuel injection valves of a type which is compact in size, light in weight and easy to produce.
2. Description of Related Art
Hitherto, various types of fuel injection valves are proposed and put into practical use particularly in the field of automotive internal combustion engines. Some of them are shown in Laid-open Japanese Patent Application (Tokkai) 2000-08990 and Laid-open German Patent Application (DE) 19547406A1. The fuel injection valves of these references are of a type that generally comprises a tubular metal case, a valve element axially movably received in the metal case, a solenoid coil disposed about the metal case and a plastic cover applied on both the metal case and the solenoid coil by means of injection molding technique. However, in the fuel injection valves of this type, compactness and weight reduction have been difficult due to some reasons. One reason is a difficulty with which the thickness of wall of the tubular metal case is reduced. That is, if the thickness is simply reduced, the metal case fails to have a sufficient mechanical strength bearing a marked pressure applied thereto when the injection molding is applied thereto. The other reason is a complicated shape which the tubular metal case has. In fact, the metal case is constructed to have stepped portions. Thus, the fuel injection valves of the publications tend to have a bulky and heavier construction.
It is therefore an object of the present invention to provide a fuel injection valve which is compact in size, light in weight and easy to produce.
According to a first aspect of the present invention, there is provided a fuel injection valve which comprises a tubular metal case constructed of a magnetic material in and through which a fuel is to flow, the tubular metal case having one open end; a valve seat tightly received in the open end of the tubular metal case, the valve seat having a fuel outlet formed therein; a valve element axially movably received in the tubular metal case, the valve element being movable between a closed position wherein a valve body of the element closes the fuel outlet and an open position wherein the valve body opens the fuel outlet; and an electromagnetic actuator disposed about the tubular metal case to actuate the valve element to move between the closed and open positions, wherein the tubular metal case is constructed of a ferritic stainless steel containing Titanium.
According to a second aspect of the present invention, there is provided a fuel injection valve which comprises a tubular metal case constructed of a magnetic material in and through which a fuel is to flow, the tubular metal case including a first portion with one end, a second portion with the other end and a third portion extending between the first and third portions; a valve seat tightly received in the first portion of the metal case, the valve seat having a fuel outlet formed therein; a valve element axially movably received in the third portion of the metal case, the valve element being movable between a closed position wherein a valve body of the element closes the fuel outlet and an open position wherein the valve body opens the fuel outlet; an electromagnetic actuator disposed on and about the third portion of the metal case to actuate the valve element to move between the closed and open positions; a plastic cover applied mainly onto the second portion of the metal case through an injection molding, wherein the first portion of the metal case has a wall thickness which ranges from approximately 0.1 mm to 0.9 mm, the second portion of the metal case has a wall thickness which is greater than that of the first portion by at least approximately 0.1 mm, and the third portion of the metal case has the same wall thickness as one of the first and second portions.
Other objects and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings.